Indicating fuse plug



Jan. 19, 1937. H. M. MUNCHERYAN INDICATING FUSE PLUG Filed April 23, 1936 7 ,449/74 0 w l/c f/emw Patented Jan. 19, 1937 UNITED STATEE PATENT OFFICE Application April 23,

17 Claims.

My invention relates to a fuse plug of the general type disclosed in my co-pending application for United States Letters Patent filed March 23, 1936, Serial Number 70,262, and the principal objects of my present invention are, to generally improve upon and simplify the construction of the plug disclosed in my aforesaid pending application, as well as other forms of similar fuse plugs; and to provide simple and effective means associated with the fuse link of the plug for indicating the condition of the fuse, that is, whether or not the fuse has been blown or ruptured as a result of overloading of the circuit in which the fuse plug is located.

A further object of my invention is to provide a relatively simple, practical and inexpensive fuse adaptable for use in conventional plugs, which fuse is formed with indicating characters, for instance, letters, which when the fuse is properly applied to the plug, occupy a position immediately beneath the window or transparent area in the top of the fuse plug where said characters may be readily observed so as to show that the fuse is unblown, and which indicating characters are ruptured and partially, if not wholly, destroyed, in the event that the fuse is blown as a result of overloading, and which resuit is especially desirable where a number of fuse plug receiving sockets are mounted in a fuse box or on a panel.

A further object of my invention is, to associate with a conventional form of fuse, an attachment including characters for indicating the condition of the fuse, which characters are normally positioned directly beneath the window or transparent section in the top of the plug as long as the fuse is unblown and functioning properly, and which indicating characters will drop away from the window or be destroyed when the fuse is blown or ruptured, thereby indicating to the observer that the fuse has blown, and therefore unfit for service.

With the foregoing and other objects in view my invention consists in certain novel features of construction and arrangements of parts that will be more fully hereinafter described and claimed and illustrated in the accompanying drawing in which:

Fig. 1 is a top plan view of a fuse plug constructed in accordance with my invention.

Fig. 2 is a vertical section taken on the line 2-2 of Fig. 1.

Fig. 3 is a horizontal section taken on the line 3-3 of Fig. 2.

Fig. 4 is a perspective view of a portion of the 1936, Serial No. 75,996

fuse that forms a part of my invention, and showing the indicating characters formed integral with the fuse.

Fig. 5 is a perspective view of a modified form of the fuse and the indicating characters that 5 are formed integral therewith.

Fig. 6 is a perspective View of a form of fuse wherein the indicating characters are separately formed and secured to that portion of the fuse that is ruptured by overloading of the current.

Fig. 7 is a vertical section taken through the center of the modified form of the fuse plug.

Fig. 8 is a. perspective View of the lower porticn of the body of the form of fuse plug illustrated in Fig. 7, and also showing a ring that is 15 utilized in connection with said body for supporting the transparent material that forms the window at the top of the plug.

Referring by numerals to the accompanying drawing, and particularly to the construction illustrated in Figs. 1 to 4 inclusive, Ill designates 7 the body of the fuse, which body may be formed of porcelain, glass or other suitable insulating material, and. seated in the lower end of said body is a metal contact II that is adapted to engage the center contact of the socket into which the plug is screwed. The body In of the plug is provided with a chamber l2, and mounted onthe outer surface of the body of the plug is a shell l3 preferably of sheet metal, in which is pressed a thread in order that the plug may be screw-seated in a conventional socket.

The upper portion M of the body of the plug is slightly increased in diameter, and formed in this portion is a chamber l5 that is occupied by that 35 portion of the fuse that bears the indicating characters. Formed on the inner face of the wall of the body of the plug between the chambers l 2 and l 5 is a circumferential shoulder It on which rests the marginal portion of a disc I! preferably formed of cardboard or other suitable insulating material.

Formed in the center of this disc H, is an. aperture l8, and formed in the diametrically opposite points on the edge of said disc are notches 19 for the accommodation of the fuse that is associated with the plug.

Positioned on top of the enlarged upper end of the fuse body is a disc 20 of transparent fireproof material, preferably mica, in order to form a window in the top of the plug through which the indicating characters of the fuse may be readily observed, and this disc is retained in p nition on the upper end of the plug by a ring 2| preferably formed of sheet metal, that is pressed around the upper end of the plug, and which overlies the marginal portion of said disc.

The fuse used in my improved plug is formed from a narrow strip or ribbon of suitable metal, and formed integral therewith and constituting a part of the fuse are characters, for instance, the letters 0. K., and the central portions of these letters are united by a narrow portion 22 of the fuse and which portion blows or is ruptured in the event of an overload of current.

The wider portions of the fuse to the sides of the indicating characters constitute a relatively long leg or portion 23, and a shorter leg or portion 24.

When the fuse is properly positioned within the plug, the indicating characters and the link or section 22 connecting the same are located directly beneath the transparent disc 20, as illustrated in Figs. 1 and 2, where they are readily visible to an observer, and the longer leg 23 of the fuse is extending downwardly onto the upper surface of the disc I1, thence outwardly and downwardly through one of the notches IS in said disc, thence inwardly upon the shoulder l6 and thence downwardly through a groove 25 that is formed in the inner face of the wall of the plug body and the lower end of this leg is electrically connected to center contact II.

The opposite shorter leg 24 extends from the indicating character to which it is connected downward, and thence outward on the upper surface of disc l'l, thence downwardly through one of the notches l9 and through an aperture 26 that is formed through the body of the plug between the lower and upper parts In and I4 thereof, and the lower end of this leg is electrically connected to threaded shell l3.

When this form of plug is in service, and the indicating characters appear intact and in proper position beneath the window at the top of the plug, an observer will understand that the fuse is unblown and therefore functioning properly.

In the event that the fuse is blown, the link or portion 22 connecting the indicating characters will be ruptured, and said indicating characters will be blown apart and in some instances partially, if not entirely destroyed, so that an observer noting the condition of the fuse below the window in the top of the plug will understand that the fuse has blown, and that the plug is no longer serviceable.

In the modified construction illustrated in Fig. 5, I have shown the indicating characters 21 formed integral with the upper end of a short arm 28, and the latter being formed integral with the narrow portion or link 29 that connects the wider end portions 30 of the fuse.

In this construction, all parts of the fuse, including the indicating characters, are cut or stamped from suitable flat sheet metal and after being cut, the arm or portion 28 is bent at right angles to the link or portion 29 and the indicating characters 21 are then bent so that they will occupy a position parallel with the transparent disc 20 when the fuse is properly positioned in the plug.

Where this form of fuse is utilized and the narrow portion 29 is blown or ruptured as a result of overload of current, the member 28 and indicating characters 21 will be thrown sidewise and partially, if not entirely, destroyed, and an observer noting this condition of the indicating characters will understand that the fuse has blown and that the plug is unfit for service.

In the modified construction illustrated in Fig.

aocmv'f 6, a separately formed leg or standard 3| has its lower end suitably connected to the narrow portion 32 of the fuse, and which narrow portion is ruptured or blows as a result of overload of current, and the upper end of this leg or standard carries the indicating characters 33.

In this form of fuse, the standard 3i and indicating characters may formed suitable nonconducting or insulating material, and when the narrow portion 32 of the fuse is blown or ruptured, the standard and indicating characters will drop or be thrown to one side or the other so as to show that the plug is unserviceable due to the blowing of the fuse.

In the modified construction illustrated in Figs. '7 and 8, the plug body is formed in two parts from suitable insulating material such as porcelain, glass or the like, and the lower part 34 is provided with a chamber 35. Formed on the lower portion of the lower part 34, is a circumferential flange 36, and seated in the closed lower end of the lower part is a contact 3'] that is adapted to engage the center contact of the socket into which the plug is screwed. The upper part 38 of the plug body is in the form of a short tubular member that fits snugly upon the upper portion of the lower member 34 above flange 38, and the two parts of the body are held in assembled relation by a metal shell 33 in which is pressed a thread for engagement with the thread of the socket in which the plug is positioned, and the lower end of this shell is flanged inwardly beneath flange 36, as designated by 4b. Resting on the upper end of the wall of body member 34, is a disc 4| of cardboard or other thin insulating material, in the center of which is formed an aperture 42, and there being diametrically opposite notches 43 formed in the edge of said disc.

Formed in the inner face of the wall of body member 38 adjacent to the upper end, is a shoul der 44 that provides a bearing for the marginal portion of disc 45 of transparent :mmilating material preferably mica, and interposed between the marginal portions of disc 4| and the transparent disc 45 is a ring 46 of cardboard or other suitable insulating material that provides a spacer to hold said discs in proper spaced relation.

The fuse utilized in this form of plug is preferably formed in a single piece from suitable sheet metal and comprises indicating characters 4?, for instance, the letters 0. K. and the same are united by a relatively narrow portion or link 48 that is blown or ruptured in the event of an overload of current.

The leg 49 or portion of the fuse that projects from one of the characters 41' extends downwardly onto the top of disc 4i, thence through one of the notches 42, thence downwardly through a groove that is formed in the inner face of plug body member 34 and the lower end of this leg is electrically connected to contact 3'1. That portion of the fuse that extends from the other one of the indicating characters extends downward onto the top of disc 4!, thence downwardly through the corresponding notch 43, thence downwardly as designated by 50, between the walls of the plug body members 34 and 38, thence between the lower end of body member 38 and flange 36, thence upwardly on the outer face of body 1nember 38, as designated, and the upper end of this last-mentioned portion of the fuse is electrically connected to the upper portion of the threaded shell 39.

Thus the indicating characters 47 are positioned directly below the transparent disc 45 and the condition of said indicating characters indicates to an observer the condition of the plug.

If desired, the upper surface of the indicating characters of the fuse may be distinctly colored so as to be more easily observed by the inspector.

The discs I! and 4| that are utilized in my improved plugs below or behind that portion of the fuse that carries the indicating characters provide a background which, if distinctly colored with respect to the color of the fuse, renders the latter more readily visible during inspection.

When the fuse blows, the gases developed by the melting of the metal in the fuse, in nearly all instances, discolors the inner face of the window in the plug, thereby, together with the destruction of the indicating characters, showing that the fuse has blown. The provision of the aperture in the disc below the fuse, permits the gases developed by the blowing of the fuse to expand downwardly into the chamber below said disc.

Thus it will be seen that I have provided an indicating fuse plug that is very inexpensive of manufacture, relatively simple in construction and very effective in performing the functions for which it is intended.

It will be understood that minor changes in the size, form, and construction of the various parts of my improved indicating fuse plug may be made and substituted for those herein shown and described without departing from the spirit of the invention, the scope of which is set forth in the appended claims.

I claim as my invention:

1. In an indicating fuse plug, the combination with a plug body having a chamber, a window at one end of said chamber and spaced contacts, of a fuse electrically connecting said spaced contacts, a fusible portion of which fuse is positioned immediately adjacent the window in said fuse plug, said portion constituting current carrying fuse condition indicating characters.

2. In an indicating fuse plug, the combination with a plug body having a chamber, a window at one end of said chamber and spaced contacts, of a fuse electrically connecting said spaced contacts, a portion of which fuse is positioned immediately adjacent the window in said fuse plug, said portion comprising current carrying characters to indicate the condition of the fuse and a relatively narrow fuse member connecting and spacing said characters.

3. In an indicating fuse plug, the combination with a plug body having a chamber, a pair of spaced contacts and a window at one end, of a partition of insulating material located within the plug body and dividing the space therein, into two expansion chambers, a fuse arranged within said plug body and electrically connecting the two contacts thereof, a portion of which fuse occupies the expansion chamber between said partition and window and said portion including fuse-condition indicating characters and a fusible element connecting and spacing said characters.

4. In a fuse plug, a plug body formed in two parts, a threaded shell mounted on said parts for holding the same in assembled relation, said shell constituting a contact, a second contact carried by one of the parts of said body, a transparent member arranged in the other part of the body which transparent member bears against an annular shoulder formed within said body, a partition of insulating material arranged between the parts of said body and dividing the space therein, into two expansion chambers, a ring arranged between the marginal portions of said disc and supporting said transparent member against said shoulder, a fuse electrically connecting said threaded shell and said contact and a portion of which fuse extends through the chamber between said partition and window.

5. In a fuse plug, a fuse having integral current carrying fuse-condition indicating characters.

6. In a fuse plug, a fuse having integral fusible current carrying fuse-condition indicating characters and a relatively narrow fuse portion electrically connecting said characters.

'7. In a fuse plug, a fuse having a relatively narrow portion that is adapted to blow or rupture as a result of overload of current through the fuse and current carrying fuse-condition indicating characters carried by said relatively narrow portion.

8. In an indicating fuse plug, a plug body having a chamber, a window at one end of said cham ber, a partition arranged within the chamber in said plug body adjacent said window, a pair of spaced contacts carried by the plug body, a fuse electrically connecting said spaced contacts, a portion of which fuse extends between said window and said partition and current carrying indicating characters forming that portion of the fuse that is positioned between said window and partition.

9. In an indicating fuse plug, a plug body having a chamber, a window at one end of said chamber, a partition arranged within the chamber in said plug body adjacent said window, said partition having an aperture, a pair of spaced contacts carried by the plug body, a fuse electrically connecting said spaced contacts, a portion of which fuse extends between said window and said partition and current carrying fuse condition indicating characters forming that portion of the fuse that is positioned between said window and partition.

10. In an indicating fuse plug, a body provided with a chamber and with an annular shoulder formed in said chamber near one end of the body of the plug, a window formed at the end of the plug body adjacent said shoulder, a partition of insulating material having its marginal portion resting upon said shoulder and dividing the space within the plug body into two expansion chambers, there being an aperture formed in said partion, a pair of spaced contacts carried by the plug body, a fuse connecting said contacts, a portion of which fuse passes through said partition and that portion of the fuse that occupies the chamber between the partition and window constituting current carrying fuse condition indicating characters.

11. In an indicating fuse plug, a body provided with a chamber and with an annular shoulder formed in said chamber near one end of the body of the plug, a window formed at the end of the plug body adjacent said shoulder, a partition of insulating material having its marginal portion resting upon said shoulder and dividing the space within the plug body into two expansion chambers, there being an aperture formed in said partion, a pair of spaced contacts carried by the plug body, a fuse connecting said contacts, a portion of which fuse passes through said partion and that portion of the fuse that occupies the chamber between the partition and window constituting spaced current conducting fuse indicating characters and a'narrow fuse portion electrically connecting said spaced characters.

12. In an indicating fuse plug, a body provided 75 with a chamber and with an annular shoulder formed in said chamber near one end of the body of the plug, a window formed at the end of the plug body adjacent said shoulder, a partition of insulating material having its marginal portion resting upon said shoulder and dividing the space within the plug body into two expansion chambers, there being an aperture formed in said partition, 2. pair of spaced contacts carried by the plug body, a fuse connecting said contacts, a portion of which fuse passes through said partition and that portion of the fuse that occupies the chamber between the partition and window constituting current conducting fuse indicating alphabetical characters that are ruptured or destroyed as a result of an overload of current through said characters.

13. In an indicating fuse plug, a body provided with a chamber and with an annular shoulder formed in said chamber near one end of the body of the plug, a window formed at the end of the plug body adjacent said shoulder, a partition of insulating material having its marginal portion resting upon said shoulder and dividing the space within the plug body into two expansion chambers, there being an aperture formed in said partition, a pair of spaced contacts carried by the plug body, a fuse connecting said contacts, a portion of which fuse passes through said partition so that it occupies the chamber between said partition and said window and that portion of the fuse in the chamber between said partition and window comprising legs that rest on said partition and current carrying fuse condition indicating characters connecting said legs.

14. In a fuse plug, a fuse having a relatively narrow portion that is adapted to rupture as a result of overload of current through the fuse, a rigid arm secured to and projecting from said relatively narrow fuse portion and fuse condition indicating characters secured to said arm.

15. In an indicating fuse plug, a plug body having a chamber, a partition dividing the chamher in said body into two expansion chambers, there being an aperture formed in said partition, a pair of contacts carried by the fuse body, a fuse connecting said contacts, a portion of which fuse extends through said partition and that portion of the fuse that extends through the partition, including a current conducting fuse condition indicating character.

16. In an indicating fuse plug, the combination Witha plug body having a chamber, a window at one end of said chamber and spaced contacts, of a fuse electrically connecting said spaced contacts, a relatively narrow fusible portion of which fuse is positioned adjacent the window in said fuse plug and said relatively narrow portion, including a current carrying fuse condition indicating character.

1'7. In an indicating fuse plug, the combination with a plug body having a chamber, a window at one end of said chamber and spaced contacts, of a fuse electrically connecting said spaced contacts, a relatively narrow fusible portion of which fuse is positioned adjacent the window in said fuse plug, said relatively narrow portion, including a current carrying fuse condition indicating character and a perforated partition located in the chamber within the plug body below that portion of the fuse having the condition indi cating character.

HRAND M. MUNCHERYAN. 

